Motor

Abstract

A motor having a compact volume by reducing sizes in axial and radial directions includes a stator, and a rotor arranged outside the stator and rotated by electromagnetically interacting with the stator, wherein the rotor includes a ring-shaped back yoke, a plurality of magnets separately arranged inside of the back yoke along a circumferential direction of the back yoke, and a frame arranged to combine the back yoke and the plurality of magnets, and having an open side through which an outer surface of the back yoke is exposed to an outside of the frame.

What is claimed is: 
     
       1. A motor comprising:
 a stator; and 
 a rotor arranged outside the stator and configured to be rotated by electromagnetically interacting with the stator, 
 wherein the rotor comprises:
 a ring-shaped back yoke including:
 a first sticking projection protruding from an axial surface of the back yoke in an axial direction, and 
 a plurality of projections extending from an inner circumferential surface of the back yoke toward a center of the back yoke and arranged separately in a circumferential direction of the back yoke, 
 
 a plurality of magnets separately arranged along the inner circumferential surface of the back yoke, and 
 a frame arranged to support the back yoke and the plurality of magnets, 
 wherein an outer circumferential surface of the back yoke is exposed to an outside of the frame, 
 the frame includes:
 a plurality of columns arranged along a circumference of the frame so as to form a plurality of magnet holes respectively formed between the columns, the plurality of magnet holes facing the inner circumferential surface of the back yoke to respectively receive an inner surface of each of the magnets, and the columns each having a groove in which a projection among the plurality of projections extending from the inner circumferential surface of the back yoke is inserted, and 
 a second sticking projection protruding in an opposite direction to the first sticking projection from an axial surface of the frame to correspond to the first sticking projection, and 
 the first sticking projection is arranged to be interlocked with the second sticking projection to prevent the back yoke from being rotated relative to the frame. 
 
 
 
     
     
       2. The motor of  claim 1 , wherein each of the plurality of projections is arranged between respective adjacent magnets among the plurality of magnets to maintain a predetermined distance between the respective adjacent magnets. 
     
     
       3. The motor of  claim 2 , wherein a thickness of each of the plurality of projections in a radial direction of the back yoke is smaller than thickness of each of the plurality of magnets in the radial direction of the back yoke. 
     
     
       4. The motor of  claim 3 , wherein the thickness of each of the plurality of projections is t 1  and the thickness of each of the plurality of magnets is t 2 , and meet the following equation:
     t 2/5< t 1< t 2/2. 
 
     
     
       5. The motor of  claim 1 , wherein the rotor further comprises:
 a shaft support configured to receive a shaft so as to be fixed to the shaft support to rotate with the rotor, the shaft support also being configured to be mounted to the frame, and 
 wherein the frame is provided to support the back yoke, the plurality of magnets, and the shaft support. 
 
     
     
       6. The motor of  claim 5 , wherein the rotor is integrally formed with the frame being injection molded between the back yoke, the plurality of magnets, and the shaft support. 
     
     
       7. The motor of  claim 1 , wherein the rotor and the back yoke have a same outside diameter. 
     
     
       8. The motor of  claim 1 , wherein the stator comprises a stator core, an insulator arranged to cover the stator core, and a plurality of wires wound on the insulator and connected respectively to terminals of phases U, V, and W, and
 wherein some of the plurality of wires are wound from a first side of the insulator along an arc-shaped wall formed in a center of the insulator, and some of the plurality of wires are wound from a second side of the insulator, opposite to the first side, along the arc-shaped wall formed in the center of the insulator. 
 
     
     
       9. The motor of  claim 8 , wherein the plurality of wires comprise
 a first wire connecting a coil of U 1  phase terminal to a coil of U 2  phase terminal, 
 a second wire connecting a coil of V 1  phase terminal to a coil of V 2  phase terminal, and 
 a third wire connecting a coil of W 1  phase terminal to a coil of W 2  phase terminal. 
 
     
     
       10. The motor of  claim 9 , wherein
 the first wire is wound from the first side of the insulator along the arc-shaped wall in a first direction, 
 the second wire is wound from the first side of the insulator along the arc-shaped wall in a second direction opposite to the first direction, and 
 the third wire is wound from the second side of the insulator along the arc-shaped wall in the first direction or the second direction. 
 
     
     
       11. The motor of  claim 10 , wherein the first wire is arranged separately from the second wire in an axial direction of the motor to avoid contacting the second wire when the first wire is wound from the first side of the insulator along the arc-shaped wall. 
     
     
       12. The motor of  claim 11 , wherein the insulator comprises a first bottom wall arranged to support the first wire and a second bottom wall arranged to support the second wire, and
 wherein the first bottom wall and the second bottom wall are formed to have a step in the axial direction for the first wire and the second wire to be separated in the axial direction.